The invention relates to a driving dynamics control or regulating system and method for a two-track, two-axle motor vehicle having only one driven axle. For the rolling moment support, a system is provided for changing the distribution of the wheel contact forces to the left and right wheel, respectively, of each axle, the fractions of the rolling moment support taken over by the front axle and by the rear axle being changeable as a function of a marginal condition. With respect to the known state of the art, reference is made, for example, to German Patent document DE 697 13 694 T2.
From DE 697 13 694 T2, it is known that, by generating a so-called rolling counter-moment in the chassis of a motor vehicle, the latter can be stabilized when cornering. While taking into account the actual vehicle speed, the angle of steering lock, and the difference between a desired value for the yaw rate derived therefrom and the actual yaw rate value, the fraction of the rolling counter-moment applied to the stabilizer bar of the rear vehicle axle is increased with respect to that at the front axle if the actual yaw value is smaller than the desired yaw value, whereupon a less understeering vehicle handling occurs. In contrast, if the actual yaw rate value is greater than the desired yaw rate value, a vehicle handling occurs which has the tendency to oversteer, and which is counteracted in that the fraction of the rolling counter-moment applied to the stabilizer bar of the rear vehicle axle is reduced and the rolling counter-moment fraction at the front vehicle axle is correspondingly increased. This known system is thus equipped with a yaw rate controller.
However, the present invention relates to a system for controlling or automatically controlling the driving dynamics of a two-track, two-axle motor vehicle having only one driven axle, which, for the rolling moment support, has a system for changing the distribution of the wheel contact forces to the left and right wheel respectively of each axle, the fractions of the rolling moment support taken over by the front axle and by the rear axle being changeable as a function of a marginal condition. That is, a system according to the present invention does not have to contain a yaw rate controller. On the contrary, a different distribution of the rolling moment support between the front axle and the rear axle of the vehicle can also take place as a function of other marginal conditions, thus, for example, as a function of the driving speed of the vehicle and as a function of the marginal condition explained in the following, which is the content of the present invention, or also of the latter alone. The present invention is based on the following problems.
By way of the open differentials usually installed today, the propulsion power is distributed by 50% respectively to the two wheels of the driven vehicle axle. In the following, a driven rear axle is used as the basis without, however, limiting the present invention thereto. When the lateral acceleration of the vehicle is too high, the contact force at the rear wheel, which is on the inside during the cornering, may now no longer be sufficient for converting the drive torque provided by the vehicle drive assembly to longitudinal force. As a result, the wheel may, as it were, “break away”; that is, the wheel traction becomes poorer and there is the threat of power oversteering. In the, so far, conventional state of the art, such a “breaking-away of the wheel is avoided by a targeted braking intervention which, however, is disadvantageous because driving energy is hereby virtually unnecessarily destroyed and the wear of the vehicle braking system is increased. Finally, such braking interventions are noticeable to the driver and are, therefore, performed at the expense of comfort.
It is an object of the present invention to provide a solution for the described problems.
The solution of this task with respect to a system for controlling or automatically controlling the driving dynamics is characterized in that the drive torque provided by the drive assembly of the motor vehicle (or a quantity firmly connected therewith) represents a marginal condition by which the fractions of the rolling moment support are changed as a function of the marginal condition. Advantageous developments and further developments are described herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.